class Solution {
public:
    int dx[4]={0,0,1,-1};
    int dy[4]={1,-1,0,0};
    int m;
    int n;
    int ret;
    int path;
    bool check[20][20];
    int getMaximumGold(vector<vector<int>>& grid) {
        m=grid.size();
        n=grid[0].size();
        for(int i=0;i<m;++i)
        {
            for(int j=0;j<n;++j)
            {
                if(grid[i][j]!=0)
                {
                    check[i][j]=true;
                    path+=grid[i][j];
                    dfs(grid,i,j);
                    path-=grid[i][j];
                    check[i][j]=false;
                }
            }
        }
        return ret;
    }

    void dfs(vector<vector<int>>& grid,int i,int j)
    {
        ret=max(ret,path);
        for(int k=0;k<4;++k)
        {
            int x=dx[k]+i;
            int y=dy[k]+j;
            if(x>=0&&x<m&&y>=0&&y<n&&
            check[x][y]==false&&grid[x][y]!=0)
            {
                check[x][y]=true;
                path+=grid[x][y];
                dfs(grid,x,y);
                path-=grid[x][y];
                check[x][y]=false;
            }
        }
    }
};
